Material working machines

ABSTRACT

In a material working (e.g. penetrating, loading, compacting) machine the power and machine weight needed to achieve a given performance can be reduced by making one (50) of two pivots (34, 50) at which a working implement such as a bucket 14 is supported an eccentric pivot and driving it by means of a motor (36). The circular vibration of the bucket at pivot (50) combined with arcuate vibration which results and is permitted at pivot (34) by means of link (30), causes the working portion namely bucket teeth (56), to vibrate on a closed elongate curved path 58. This improves penetration and loading performance of the bucket without requiring excessive power to generate the vibrations.

This invention relates to material working machines such as excavators,loaders, drills or breakers, and compactors having an implement forworking on material in some way. Throughout this specification the term"working" on material is intended to encompass all forms of interactionof a working implement with material being worked on, for example,penetration, compaction, loading and transportation etc. of materials.

Commonly, material working machines comprise a "prime mover", which issome form of powered vehicle, to which is articulated support meanscarrying a working implement. A system of hydraulically powered ramsmounted on booms is used to impart rotational and/or translatorymovement to the working implement. Typical examples are back hoes inwhich the working implement is a bucket used to dig into the ground andtowards the prime mover then lift excavated material out of the ground,and front loaders in which the working implement is also a bucket but isarranged to be driven generally horizontally into material then tiltedand raised to lift the material collected. In use, such machines,especially earth working machines, may encounter very high resistance atthe working implement and in "deadweight" machines this resistance mustbe overcome using forces generated by the rotational and/or translatorymovement of the working implement, the available level of such forcesbeing dependent on the weight of the prime mover, the support means andthe working implement and the reach of the working implement. Indeadweight back hoes, to achieve the same working capability but alonger reach, for example, it would be necessary to increase the weightof the prime mover to ensure penetration without the prime mover liftinginstead. In deadweight front loaders, to achieve greater tractive effortto force the bucket into more resistive loads, it would be necessary toimprove ground grip by increased weight of the prime mover and/orresorting to crawler tracks instead of ground wheels.

It is known to vibrate a working implement mounted on a material workingmachine.

In proposed forms of material working machines utilising vibratingbucket or blade type implements which penetrate the ground, a straightor slightly arcuate linear reciprocating movement is imparted to theportion of the working implement in contact with the material beingworked but such "dynamic" arrangements have not in practice proved to beof very great advantage.

Straight reciprocation of a drilling spike is satisfactory forpenetration but often the spike becomes wedged in the hole it hasdrilled.

Road rollers have been vibrated by means of mechanically rotatedunbalanced weights but the resultant vibration of the roller is of anuncontrolled form and unsuited to other applications.

The present invention provides a material handling machine having meanssupporting an implement for working on material, the machine comprisinga material working machine having means supporting an implement forworking on material, the machine comprising means for vibrating theimplement by applying a mechanically predetermined movement to theimplement such that, in use, a portion of the implement for engagingmaterial to be worked on describes a closed curve during each cycle ofvibration. This form of vibration has the advantage that a higherfrequency is obtainable for a given vibratory power input than withlinear reciprocation, which wastes power due to the motion beingdiscontinuous.

The resistance presented by the material being worked on is then muchmore easily overcome enabling the same working capability to be achievedusing lighter equipment. Dynamic machines which are cheaper, lighter andhave a longer reach can thus perform as well as deadweight machineswhich are heavier, more expensive and of shorter reach. When using theinvention in certain machines, the tractive forces between the primemover and the ground need not be as great as in deadweight machineswhich may enable, for example, wheels to be used instead of the crawlertreads which would otherwise be necessary. Another advantage of machinesutilising the invention is that suction problems, often encountered byearth working equipment when the ground material is wet, are reduced oravoided due to the motion of the working implement.

The present invention enables high frequency movement of the workingportion of the working implement to be obtained due to the continuousnature of the motion imparted to the working implement. Frequencies ashigh as 170 Hertz can be obtained and a frequency above 8 Hertz ispreferred.

Preferably the closed curve is of elongate form. With this preferredfeature the vibratory movement of the working portion of the implementhas directional characteristics which can be utilised to substantialbenefit whilst enabling high frequency movement to be achieved, byarranging for the major dimension of the elongate curve to be at anappropriate angle.

For example, in one form of the invention, the support means andimplement are in a back hoe configuration, the implement being aback-hoe bucket, and the closed curve described by the leading edgeportion of the bucket is disposed with its major dimension at an acuteangle, substantially less than a right angle, to the direction in whichthe leading edge portion of the bucket extends forwardly. Such anarrangement optimises the benefits of the vibration when a back hoe isbeing used to excavate in its normal manner, by reducing the resistanceoffered by the ground being excavated.

In another example the support means and implement are in a front loaderconfiguration, the implement being a bucket, and the closed curvedescribed by the leading edge portion of the bucket is disposed with itsmajor dimension approximately perpendicular to the direction in whichthe leading edge portion of the bucket extends forwardly. This enablesloosening and thus easier penetration of the material being loaded.

In a preferred embodiment of the present invention the vibrating meanscomprises an eccentric on a shaft and drive means are provided forrotating the shaft.

In some forms of material handling machines in which the workingimplement can be vibrated, forces which are used to effect rotationaland/or translatory movement of the working implement are applied alongthe same path as forces which are used to effect vibratory movement ofthe implement. Thus the means for producing vibration of the workingimplement has to work against the other applied forces and in some casesagainst the entire weight of the machine.

According to another aspect of the present invention, we provide amachine having means supporting an implement for working on material,the machine being adapted to apply vibratory forces for vibrating theimplement and also means for applying rotatory and/or translatory forcesfor effecting rotational and/or translatory movement of the implementwherein the vibratory forces are applied along a different path from atleast the major rotatory and/or translatory forces.

This aspect of the invention has the advantage that the means forproducing vibration of the working implement need be less powerful thanpreviously required in known types of machine thereby saving on costsand materials.

With an elongate closed curve vibration path, the orientation of themajor dimension of the path relative to the direction of the majorrotatory and/or translatory forces may be arranged so as to enhance orachieve the same effect.

According to yet another aspect of the present invention we provide amachine comprising means supporting an implement for working on materialwherein the implement is coupled to a driven eccentric and is caused tovibrate by rotation of the eccentric.

The support means will in many cases support the working implementthrough pivots which enable rotation of the implement, e.g. thebucket-loading movement of a back hoe or the bucket-tilting movement ofa front loader, and the driven eccentric advantageously itself forms oneof these pivots, thus having a dual function and reducing the cost ofincorporating the invention into material working equipment of otherwiseknown design, since the driven eccentric simply substitutes for theusual coaxial pivot.

Preferably, the eccentric cooperates with a bearing fixed relative tothe implement.

In connection with all three aspects of the present invention,preferably the support means pivotally supports the implement at atleast two spaced positions, the vibrating means being arranged to applyvibration to the implement at one said position, and a control member ofthe support means being pivotally coupled to the implement at anothersaid position so as to control the position of the implement whilepermitting said vibration.

Preferred embodiments of the present invention will now be described byway of example with reference to the accompanying drawings, in which:

FIG. 1 is a side view of the relevant part of a material working machineaccording to the present invention incorporating an excavatorpenetrating and loading member which is a back hoe attached to acarrying vehicle (not shown) with a pivotal or slewing mount;

FIG. 2 is a front view of the excavator of FIG. 1 looking in directionY;

FIG. 3 is a partial cross-sectional view taken along the line III--IIIof FIG. 2;

FIG. 4 is a cross-sectional view taken along the line IV--IV in FIG. 3;

FIG. 5 is a side view of the relevant part of a material working machineincluding a front loader, which forms a second embodiment of the presentinvention;

FIG. 6 shows a detail from FIG. 5; and

FIG. 7 shows a complete earth moving machine incorporating the excavatorof FIGS. 1 and 2.

In FIG. 1, an excavator indicated generally at 10 forming part of amaterial working machine comprises support means indicated generally at12 and a bucket 14. A main support 16 is pivotally connected to apivotal boom structure 18 about pivots 20 and 22. A boom ram 24 isoperable to lift and lower the bucket 14 by pivoting the main support16.

A vibratory mechanism, indicated generally at 26, is mounted on the mainsupport 16. A ram 28 operable to impose rotational movement of thebucket 14 is connected at pivot 31 to pivotal links 30 and 32. Link 32is pivotally connected at pivot point 33 to the main support 16. Thepivotal link 30, connected to the bucket 14 at pivot 34, is operable tocontrol the position of the bucket 14 while permitting it to vibrate, aslink 30 swings to and fro about pivot 31.

Referring now both to FIG. 1 and to FIG. 2, the vibrating mechanism 26comprises two aligned hydraulic motors 36 and 38 connected to a commonshaft 39 having a drive sprocket 40 mounted thereon, which is connectedby drive chain 42 to another drive sprocket 44. The sprocket 44 ismounted on a shaft 46 each end of which is sealed in an inner bearinghousing 48. At each end of the shaft 46 is an eccentric portion 50sealed in an outer bearing housing 52. The position of the bucket 14 isfixed in relation to the outer bearing housings 52 by means of rigidconnecting portions 54.

The hydraulic motors 36, 38 drive the shaft 39 causing the drivesprocket 40 to rotate and this rotation is transmitted to the drivesprocket 44 via chain 42. The shaft 46 rotates causing the eccentrics 50to describe a circular orbit (having a radius of less than 1 cm, and,for example, about 1 mm) around the axis of the shaft 46 therebyvibrating the bucket 14 in a manner which is controlled by line 30connected to the link 32 and ram 28. With this arrangement, theeccentrics 50 cause the teeth 56 on the bucket 14 to describe agenerally elliptical closed curve during each cycle of vibration. InFIG. 1 the motion of the teeth 56 is diagrammatically indicated at 58showing that the major dimension of the elongate path is at an acuteangle, substantially less than a right angle, to the direction in whichthe toothed leading edge portion of the bucket extends forwardly, whichwill be approximately the direction of incidence of the teeth 56 on thematerial to be penetrated. This configuration has two advantages.Firstly, throughout a substantial portion of the motion, the teeth arenot acting against the weight of the machine behind them and, secondly,the resistance of material being worked is more easily overcome by tosome extent working the surface of the material rather than attemptingto thrust into the body of the material.

The frequency of vibration may, when there is no load, be about 30-50Hertz but is permitted to vary throughout the excavating cycle of themachine 14. The hydraulic motors 36 and 38 are pressure compensatedmotors of a type obtainable from RHL Hydraulics of Planet Place,Killingworth, Newcastle-upon-Tyne, England in which, as the outputtorque rises, the output speed falls, thus giving a substantiallyconstant power output. An exemplary motor is Type LM of RHL Hydraulics,Ltd. When in the penetrating mode, that is, when the teeth 56 areinitially entering the material to be worked, the load on the motors isrelatively low so that the vibration frequency will be relatively high,giving maximum assistance to penetration. As penetration becomes deeper,so the load on the motors becomes relatively great so that the torquedemand rises causing a corresponding reduction in the motor speed sothat the frequency of the vibration is reduced. This automatic frequencyreduction in response to increased load enables vibration to bemaintained without stalling occurring, using less power than wouldotherwise be needed, and hence smaller and lighter motors.

The rotational movement of the bucket 14 about pivot position 34 and theeccentrics 50 also affects the motion described by the teeth 56--thecloser that pivot 31 moves towards the eccentrics 50, the greater thelength of the longitudinal axis of the motion 58 and vice versa.

Returning now to FIG. 3, the inner bearing housing 48 is bolted to themain support 16 and contains a roller bearing 60 which abuts a shoulder62 provided in the shaft 46 thereby preventing sideways movement of theshaft 46. A sealing collar 64 is bolted to the housing 48 on the otherside thereof and comprises an oil seal 66 to facilitate lubrication ofthe bearing 60 and the chain 42 via passageways 68 (indicated in dottedlines).

The outer bearing 52 surrounds the eccentric 50 and contains areciprocating bearing 70. A sealing collar 72 is bolted to the bearinghousing 52 and an anti-wear collar 74 is fastened to the end of theeccentric 50 to prevent dirt or water penetration and to facilitateremoval of the complete bearing means for servicing. Oil seals 76 and 78are provided in the bearing housing 52 to retain lubricant introducedthrough a passageway 80 (shown dotted).

A main lubrication passageway 82 has a grease nipple 84 which isrecessed to provide lubrication routes to passageways 68 and 80.

In FIG. 4, the position of the eccentric 50 relative to the shaft 46 isillustrated. The eccentric is typically 1 mm. off centre. The bolts 86fix sealing collar 64 to the bearing housing 48 and the bolts 88 fix thebearing housing 48 to the main support 16. When the motors 36 and 38operate to rotate the shaft 46 the outer bearing housing 52 is displacedrelative to the inner bearing housing 48 by an amount equal to theeccentric radius.

Referring to FIG. 5, front loader mechanism of a material workingmachine is indicated generally at 100 and comprises a front loaderbucket 102 supported by a main support 104. The main support 104 ispivotally connected at 106 to a link member 108 which is in turnpivotally connected to a ram 110 at point 112, the ram 110 beingoperable to effect rotation of the bucket 102 relative to the mainsupport 104. The machine 100 comprises a vibrating mechanism, indicatedgenerally at 114, for imparting vibratory motion to the tip 116 of thebucket 102 when driven by a motor 118.

Motor 118 vibrates bucket 102 via drive chain 42, sprocket 44 and pivot46 having an eccentric portion 50 to which the fixed bucket mounting 119is pivotally mounted by a suitable bearing.

The link member 108 is pivotally attached to the bucket 102 by means ofa pivot 120 pivotally mounted in a bearing housing 122 fixed to thebucket as shown in more detail in FIG. 6. The pivot 120 is rotatablymounted by means of a bearing 121 in a bearing block which is slidablyretained between rigid plates 126 and 128 so that it can slide up anddown in the bearing housing 122. There is an oil duct (not shown) tofacilitate lubrication of the pivot 120 and bearing 121. In this way,the circular vibratory movement of the upper end of bucket 102 inducedby the vibrating mechanism 114 is accommodated by rocking rotational,and vertical translatory, movement of the pivot 120 in the bearinghousing 122. As in the previous embodiment, the movement applied to thebucket from the motors is of a predetermined form established by themechanical configuration used.

The resultant movement at the bucket tip is an elongate closed path 134having its major dimension almost perpendicular to the direction inwhich the toothed leading edge portion of the bucket extends forwardly,which is substantially the same as the direction in which the bucket 102is pushed (leftwards) by translatory movement into material to beloaded. The loosening effect of this vibration upon the material resultsin less force being needed to drive a given bucket into a given type ofmaterial.

In the embodiments described, improved forms of lubrication are asfollows. In FIGS. 1 to 4 sprockets 40 and 44 and chain 42 may becontained in an oil-charged cavity which communicates also with bearings60, while further oil charged cavities may be incorporated in bearinghousing 52 so that oil therein will be splashed or forced at bearings 70during operation, due to the rapid eccentric movement of the housings.In FIGS. 5 and 6, an arrangement as just referred to may be used tolubricate the vibrating mechanism 114, and bearing housing 122 may havean oil charged chamber therein which communicates with the bearingsurfaces of pivot 120 and block 124 to lubricate them.

In both embodiments described above, the eccentric may be driven by anyappropriate means, for example an electric motor, instead of a hydraulicmotor. The drive means may be articulated to the shaft on which theeccentric is mounted by means of a gear arrangement if desired. It isenvisaged that material working machines according to the presentinvention may be provided with automatic start and cut-off mechanisms,preferably sensing when the implement encounters a substantial load(e.g. by sensing ram pressure) and in response setting the vibrationmotor or motors running, so that a working implement is vibrated onlyduring the relevant parts of the operation cycle being performed. Inaddition, a manual override connected to the vibrating mechanism may beprovided.

It will be appreciated that, particularly in the FIG. 5 embodiment, themajor part of the force to drive or translate the implement, bucket 102,into the material is transmitted on a path through boom 104 and pivots106 and 120 whereas the vibration is applied on the parallel path of ram110, pivot 112, pivot 50. Consequently, the vibrating mechanism is nottrying to a substantial extent to bodily vibrate the vehicle carryingboom 104 nor the entire body of material bucket 102 is entering, so thepower needed to impose the vibration is less than would otherwise be. Tothe extent that vibration transmitted to the vehicle or other parts ofthe support means is a discomfort or problem it may be reduced by knownvibration absorbing couplings.

Many variations are possible. The motor or motors may drive theeccentric directly. Flywheels may be added to rotating parts to storeenergy ready for delivery when working of material begins. Other typesof implement than a bucket, e.g. an impact-drilling spike or acompacting implement with a flat or rounded base, may be attached to thesame support means as have been described and the closed path vibrationsimposed on them will enable them to carry out their function. In thecase of an impact-drilling spike the closed-path vibrations will reducethe tendency for the implement to become wedged in the hole being made.

In each case, but on a lesser scale, the invention may also be appliedto machines which are manually manoeuvred instead of mounted on a primemover.

FIG. 7 shows for the sake of completeness an entire earth moving machinewhich is conventional except for an excavator arm 10 constructed asdescribed with reference to FIGS. 1 and 2. A main motor M, for examplediesel driven, drives a hydraulic pump P which supplies pressurisedfluid to a control C which is selectively operable to supply the fluidto the motors 36, 38 to control the vibration of the bucket. The powerand control system is diagrammatically shown for simplicity and may beimplemented using well known techniques and components.

It will be apparent from the drawings that because the eccentric iscloser to the other pivot than is the working portion of the implement,the amplitude of the vibration at the working portion is greater thanthat applied at the position of the eccentric.

I claim:
 1. A material working machine having an implement for workingon said material, support means supporting said implement, means forapplying non-vibratory forces for the operation of the implement, andseparate vibratory means for applying vibratory forces for vibrating theimplement such that, in use, a working portion of the implement forengaging said material performs a closed curve motion during each cycleof vibration, wherein the vibratory means is driven by constant-powerdriving means which automatically responds to any variations in the loadapplied to the implement at any instant of its operation.
 2. A machineaccording to claim 1, wherein the driving means includes aconstant-power hydraulic motor incorporated in a hydraulic circuitindependent of any other hydraulic circuit which might be used for theoperation of the machine.
 3. A machine according to claim 1, wherein thevibratory means both vibrate and pivotally support the workingimplement.
 4. A machine according to claim 1, wherein the vibratoryforces are applied along a different path than a major part of thenon-vibratory forces.
 5. A machine according to any one of claims 1 to4, wherein mounting of the vibratory means to the implement and mountingof the driving means associated therewith are immersed in lubricant. 6.A machine according to any one of claims 1 to 4, including linkages foreffecting non-vibratory movement of the implement to enable selectivepositioning of the implement.
 7. A machine according to claim 1, whereinthe vibratory means comprises eccentric means on a shaft.
 8. A machineaccording to claim 7, wherein the eccentric means cooperate with bearingmeans fixed relative to the implement.
 9. A machine according to claim1, wherein the support means pivotally supports the implement at atleast two spaced positions, the vibratory means is arranged to applyvibration to the implement at one said position, and a control member ofthe support means is pivotally coupled to the implement at another saidposition so as to control the position of the implement while permittingsaid vibration.
 10. A machine according to claim 9, wherein the controlmember forms part of a linkage for effecting rotational movement of theimplement.
 11. A machine according to claim 9 or 10, wherein the controlmember comprises a link arm movably mounted at both ends.
 12. A machineaccording to claim 9 or 10, wherein the control member is pivotallycoupled to the implement by means of coupling units, each containing apivot received in a bearing reciprocably mounted in a bearing housing.13. A machine according to claim 4, wherein the support means pivotallysupports the implement at at least two spaced positions, the vibratorymeans is arranged to apply vibration to the implement at one saidposition and a control member of the support means is pivotally coupledto the implement at another said position so as to control the positionof the implement while permitting said vibration.
 14. A machineaccording to claim 13, wherein the control member forms part of alinkage for effecting rotational movement of the implement.
 15. Amachine according to claim 13 or 14, wherein the control membercomprises a link arm pivotally mounted at both ends.
 16. A machineaccording to claim 13 or 14, wherein the control member is pivotallycoupled to the implement by means of coupling units, each containing apivot received in a bearing reciprocably mounted in a bearing housing.17. A machine according to any one of claims 1 to 4, 7 to 10, 13 or 14,wherein the vibratory means through a gear arrangement are remotelydriven by the driving means.